We are requesting funds to purchase a CTL ImmunoSpot S6 Universal Analyzer. This instrument allows investigators primarily to perform multi-color ELISPOT analysis along with other cell- based applications. Currently, neither the research facility at the Oklahoma City VA Medical Center (OKC VAMC) nor the affiliated University of Oklahoma Health Sciences Center has this high-end ELISPOT analyzer. It is well known that immune cells play a critical role in many diseases including cancer. It is now becoming evident that changes in immune cell heterogeneity potentially impacts either positively or negatively on the disease progression. However, in the past only limited technology allowed investigators to study heterogeneity of immune cells, immune cells interaction with other cell types and their molecular impact in the tissue microenvironment and more so, immunological markers interface in tissue microenvironment and systemically. Immune monitoring is complex and better understanding requires multiplexing. CTL ImmunoSpot S6 Universal Analyzer permit multicolor T and B cell fluorospot analysis, live/dead PBMC counting, and much more. This is an attractive alternative to flow cytometry analysis. CTL ImmunoSpot S6 Universal Analyzer also allows investigators for other applications at the microscopic (single cells and subcellular particles) as well as the macroscopic level (colonies and Plaques). The primary field of application for CTL ImmunoSpot S6 Universal Analyzer has been multi-color ELISPOT analysis. CTL employs a technology specifically designed to avoid excitation cross-contamination, enabling the accurate detection of up to eight analyte co-expressing cells, including polyfunctional T cells. In addition, image analysis-based multi-parameter analysis of cells with CTL ImmunoSpot S6 Universal Analyzer can be useful with both adherent or non-adherent cells alike, and the sample size for analysis can be as low as one cell. A survey of all VA researchers at OKC VAMC showed over 80% of the researchers are potentially interested to use CTL ImmunoSpot S6 Universal Analyzer to study the modulation of antigen- specific T cell induction and activation in their research. This instrument will be used by six major users who have VA Merit grants funded or pending. We also anticipate that researchers at other VA centers will use this instrument.